At a crucial moment in John le Carré's 23rd novel, Toby Bell, private secretary to an ideologically promiscuous Foreign Office minister, needs to eavesdrop, in the present day, on a weekend meeting from which he has been excluded. Toby employs a forgotten, Nixonian recording system, which is specifically identified as "Cold War-era".

That reference to the period when Le Carré's reputation was first made – with The Spy Who Came in from the Cold, which marks its 50th anniversary this year – feels carefully planted. Although readers will hope for more from Le Carré, A Delicate Truthoften feels like a formal summation of the concerns that have occupied his fiction for five decades. Walking in the west of England in 2011, two warriors from a modern espionage war, one of whom has served in Northern Ireland, pass second world war "pillboxes covered in graffiti", thereby combining three British battlegrounds in one sentence.

This sense of a geopolitical timeline lying just under the narrative, like a listening bug under a table, is strong throughout the novel. Apart from Toby's employment of a tape recorder dated to the great spy wars between east and west, the plot is set in motion by a shady mission in Gibraltar that attempts to ambush an alleged Middle Eastern terrorist. This prologue neatly combines the location of a notorious incident from the Thatcher years (when, in 1988, three IRA operatives were shot by the SAS on the Rock) with the target and techniques of the US-UK war on terror.

When Le Carré's fictional "Operation Wildlife" subsequently becomes the subject of Whitehall scandal and cover-up, the violent death of a participant – attributed by the authorities to suicide, but disputed by conspiracy theorists – appears to allude to the case of the government weapons expert Dr David Kelly. And these public shadows overlap with a private one: Toby's climactic encounter with a diplomat who may know the truth of what happened in the British colony on the coast of Spain takes place in north Cornwall, where the author has lived for much of his adult life.

But the loudest sound in this intricately built echo chamber is of recent origin. The novel seems to draw in a broad way on the very curious period in British politics between the autumns of 2010 and 2011, when the Conservative foreign secretary, William Hague, and defence secretary, Liam Fox, were involved in controversies over questionable henchmen. Fox resigned because of questions about the involvement in meetings of Adam Werritty, a non-civil service special adviser, while an informal assistant to Hague, Christopher Myers, stepped down after reports of his close attendance on some trips.

Characteristically, Le Carré is less interested in the personal innuendo (strongly denied by both politicians) attending these strange aides than in the potential corruption of the chain of advice and the opportunities for a shadow foreign policy.

In that regard, the book completes unfinished business for the author. Confounding those who wrote off spy fiction after the official end of the cold war, the last decade in US and UK relations has been dominated by conflicts justified through secret intelligence that proved to be false. As its title strongly hints, A Delicate Truth, with a plot that again involves partisan or tactical interpretation of data, feels like a completion of Le Carré's depiction of the Bush-Blair era and the role of neo-conservative thinktanks and tickled-up information that began in Absolute Friends (2003) and A Most Wanted Man (2008).

A Delicate Truth savagely dramatises the "ever-expanding circle of non-governmental insiders from banking, industry and commerce who were cleared for highly classified information". Toby's minister, Fergus Quinn, is under the control of the unelected business-fixer, Jay Crispin. Half a century after the state-on-state espionage described in The Spy Who Came in from the Cold, spying, in common with most other enterprises, has been privatised and opened up to defence contractors such as the shadowy Ethical Outcomes Ltd in this novel – with all the potential for massaging success rates and indulging shareholder whims that privatisation entails.

Those familiar with the earlier books, though, understand that Le Carré has no nostalgia for the ways of the past but is merely offering an exhaustive and comparative history of methods of national deceit and delusion.

Le Carré has attracted a lot of interest on film recently, with Tomas Alfredson's magnificent Tinker Tailor Soldier Spy and Anton Corbijn's forthcoming A Most Wanted Man. Those experiences may have affected the new novel's strikingly fluid chronology, which blurs expertly between two periods of 2008 and one in 2011, though rarely in calendar order. However, it seems typical of Le Carré's literary integrity that, in other ways, the book defies filming, turning on a trick almost impossible to achieve on screen, in which the same character appears under two different identities without the doubling being rumbled until the storyteller chooses.

It's true that the characters are unusually vocalised, almost as if an actor is auditioning behind the dialogue, but ventriloquism has always been one of the author's central skills, making his audiobook recordings an extra treat for his readers. Every speaker has a specified accent and there is an acute ear for other verbal tells, from the casual profanity of younger characters, regardless of class, to the fact that Bell knows that he has been frozen out when the minister stops calling him "Tobe" and reverts to "Toby".

In an interview at around the time of his 75th birthday, Le Carré admitted that he feared producing in older age the sort of low-energy novellas that completed the shelf of his hero Graham Greene. But, after the disappointingly sketchy Our Kind of Traitor (2011), which relied too heavily on hectic narration, the 81-year-old Le Carré is back at full power with a book that draws on a career's worth of literary skill and international analysis. Le Carré will almost certainly follow Greene in being denied the Nobel prize for literature, but no other writer has charted – pitilessly for politicians but thrillingly for readers – the public and secret histories of his times, from the second world war to the "war on terror".